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use malloc, not xmalloc in obstack #define

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use Uli's prime code, not near-prime
(hash_initialize): don't require prime table size as input
(hash_insert_if_absent): When rehashing, choose new size that is 2N+1, not 2N.
This commit is contained in:
Jim Meyering
1997-09-17 17:06:26 +00:00
parent bba93bb711
commit 2fef57672b
1 changed files with 38 additions and 4 deletions
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lib/hash.c
+38 -4
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@@ -12,7 +12,6 @@
#include <stdlib.h>
#include <assert.h>
#include "near-prime.h"
#include "hash.h"
#ifdef USE_OBSTACK
@@ -27,6 +26,39 @@
static void hash_free_0 (HT *, int);
static int
is_prime (candidate)
unsigned long candidate;
{
/* No even number and none less than 10 will be passed here. */
unsigned long divn = 3;
unsigned long sq = divn * divn;
while (sq < candidate && (candidate % divn))
{
divn++;
sq += 4 * divn;
divn++;
}
return (candidate % divn);
}
/* Round a given number up to the nearest prime. */
static unsigned long
next_prime (candidate)
unsigned long candidate;
{
/* Make it definitely odd. */
candidate |= 1;
while (!is_prime (candidate))
candidate += 2;
return candidate;
}
static void
hash_free_entry (HT *ht, HASH_ENT *e)
{
@@ -156,15 +188,16 @@ hash_get_table_size (const HT *ht)
function is called (e.g. a second time). */
HT *
hash_initialize (unsigned int table_size,
hash_initialize (unsigned int candidate_table_size,
Hash_key_freer_type key_freer,
unsigned int (*hash) (const void *, unsigned int),
int (*key_comparator) (const void *, const void *))
{
HT *ht;
unsigned int i;
unsigned int table_size;
if (table_size <= 0)
if (candidate_table_size <= 0)
return NULL;
if (hash == NULL || key_comparator == NULL)
@@ -174,6 +207,7 @@ hash_initialize (unsigned int table_size,
if (ht == NULL)
return NULL;
table_size = next_prime (candidate_table_size);
ht->hash_table = (HASH_ENT **) malloc (table_size * sizeof (HASH_ENT *));
if (ht->hash_table == NULL)
return NULL;
@@ -336,7 +370,7 @@ hash_insert_if_absent (HT *ht, const void *e, int *failed)
if ((double) ht->hash_n_keys / ht->hash_table_size > 0.80)
{
unsigned int new_size;
new_size = near_prime (2 * ht->hash_table_size);
new_size = next_prime (2 * ht->hash_table_size + 1);
*failed = hash_rehash (ht, new_size);
}